SD playback is very important to me too. Can I infer from your answer that the LX70a is meant to be better in this regard?
SD playback is supposed to be excellent so people keep saying.
There's been some moans on layer change,though.
More in this thread: http://www.avforums.com/forums/showthread.php?t=653640
The LX70 only has HDMI 1.2 and no support for DTS-HD, so any DTS-HD disc will only play the 5.1 DTS core. Due to the HDMI 1.2 port, the LX70 cannot bitstream any HD sound format over HDMI to an amplifier that could decode them. Make sure you install the latest firmware as it will give you on-board DD+ and TrueHD decoding.
The LX70a has an HDMI 1.3 port and in addition to supporting on-board DD+ and TrueHD out of the box, can also send DTS-HD as bitstream over HDMI to a suitable amp. Like the LX70, it cannot decode DTS-HD internally.
Neither player is, or will be upgradeable to BD Profile 1.1 or higher.
If you want a Pioneer player with Profile 1.1 or higher support, new ground up designs should be available later this year. No firm dates or prices have yet been given.